Kirk Wallace wrote: > Thanks again Jon and Chris. What should have been obvious turns out to > be the problem. Graphing the encoder index shows random pulses mixed in > with the regular pulses. I really did not want this to be the problem > since I had already gone through fixing another issue with this encoder. > I guess wishing is not a valid method for repairing machinery. > > Before, I had a problem with the encoder disk position coupled with a > wobble. Now it seems to be an EMI problem because I get occasional index > pulses with the disk removed and the spindle turning. I haven't been > able to get a reliable reproduction of the fault, so I will be busy with > trouble shooting for a while. Check the grounding carefully. The best is to not have the encoder grounded to the machine frame, but grounded through the board reading the encoder signals. Shielding of the encoder cables is almost always required. Check the lay of probable interference sources like motor-VFD cables and any other that might have 120 or 240 VAC on them.
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